This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chemotherapy-related cognitive dysfunction, so called "chemobrain" is a widely reported yet poorly defined complication of chemotherapy. Although much concern has been expressed about this potential toxicity, little is know about the central nervous system changes that may result from chemotherapy administration. This proposal is designed to study 50 women with early stage breast cancer receiving commonly used chemotherapy regimens used for adjuvant treatment. In addition to cognitive testing focusing on specific cognitive problems identified from prior studies, the trial will focus on neuroanatomical and neurofunctional changes defined by magnetic resonance imaging (MRI) including both functional MRI (fMRI) examining alterations in brain activity during cognitive operations such as memory tasks, and a technique that provides exquisite imaging of the white matter integrity of the brain (diffusion tensor imaging, DTI). We will also test whether the APOE genotype, which has been related to cognitive impairment in aging and dementia, may be associated with the development of cognitive dysfunction with chemotherapy. Patients will have cognitive function testing, imaging and blood collection prior to chemotherapy treatment, after chemotherapy treatment, and at one year. The information obtained from this project will be used to define the risk and frequency of this complication and lead to further larger trials that will explore interventions.